What DSC Does
Digital Selective Calling sends digital alerts and calls on Channel 70. It can alert stations, identify the calling set, and request a voice channel.
- Digital alerts on Channel 70
- Uses MMSI identity
Marine Radio revision module 8 of 10
DSC
Digital Selective Calling
MMSI, Channel 70, routine individual calls, distress alerts, acknowledgements, and DSC follow-up voice procedure.
Ship, coast, and group MMSI structuresChannel 70 and DSC call types
9 guided lessons · 19 practice questions · 19 flashcards
3 outcomes · self-guided revision
- Explain mMSI, Channel 70, routine individual calls, distress alerts, acknowledgements, and DSC follow-up voice procedure.
- Apply Ship, coast, and group MMSI structures to a realistic onboard situation.
- Recall the core check: digital alerts on Channel 70.
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Lesson summaries
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MMSI
The Maritime Mobile Service Identity is the digital identity used by DSC equipment. It must be programmed correctly and match the licensed radio arrangement.
- Digital radio identity
- Must be programmed correctly
Routine and Distress DSC
Routine DSC can call an individual station and propose a working channel. Distress DSC alerts all DSC-equipped stations in range and must be handled with care.
- Routine individual calls
- Distress alerts
What DSC Adds
Digital Selective Calling sends digital alerts and calls using MMSI identities. It can alert coast stations or other vessels, propose a working channel, and send distress information rapi...
- DSC uses Channel 70 for digital signalling.
- MMSI identifies the station digitally.
Distress Alert Reception And Acknowledgement
When a DSC distress alert is received, stop any transmission that could interfere and maintain a listening watch on Channel 16. The voice distress message should follow.
- Cease interfering transmissions.
- Listen on Channel 16.
False DSC Distress Alert
A false DSC distress alert must be cancelled promptly and clearly. The operator should cancel the alert on the set if possible, then broadcast an all-stations voice cancellation on Channe...
- Cancel on the DSC set if the equipment allows.
- Make a voice cancellation on Channel 16.
Routine Individual DSC Calls
For a routine individual DSC call, select the other station's MMSI, choose routine priority, nominate a suitable working channel, then wait for the acknowledgement. The voice conversation...
- Use routine priority for routine traffic.
- Enter or select the correct MMSI.
MMSI Structures And DSC Call Types
An MMSI is a nine-digit digital identity. The three Maritime Identification Digits (MID) identify the administration or geographical allocation. A ship station identity normally begins wi...
Read the full lesson: MMSI Structures And DSC Call TypesPosition, Received Messages, Tests, And False Alerts
Confirm that the DSC display has a current position and UTC time from the connected navigation receiver. If the interface fails, enter position and time manually and update them as requir...
- Check automatic position and UTC; know the manual-entry fallback.
- Review the complete received message before changing channel or replying.
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